1. Field of the Invention
This invention relates to a flange type duct connector for sealingly connecting the ends of a pair of sheet metal duct sections and more particularly to the configuration of the duct connecting flange.
2. Description of the Prior Art
U.S. Pat. No. 4,508,376 discloses a flange connection for connecting the ends of generally rectangular duct sections. The duct connection includes a plurality of flange sections connected to each other by means of corner pieces having angularly extending legs. The flange sections and the corner pieces form a rectangular frame which is positioned on the end of a duct section. The corner pieces have offset lower corner portions that permit the edge of the duct to extend into sealing relation with a gasket member positioned between adjacent duct frames.
The frame sections have a front wall and a parallel rear wall with a generally rectangular opening therebetween into which the legs of the corner pieces extend. A receiver member is formed in the frame section for a mastic material in which the duct edge portion is embedded.
U.S. Pat. No. 4,566,724 discloses a duct joint frame in which the frame sections have a rear wall that extends angularly away from the frame section front wall forming a triangularly shaped opening for the corner piece. The rear wall has an inwardly bent bottom portion which terminates in a raised surface or rib against which the lower edge of the corner piece rests when the frame member is assembled. With this configuration, the rearwardly extending leg cannot be secured to the duct side wall by screws or welds.
There is a need for a duct connector frame that has flange sections with angularly extending rear legs to provide improved support for the corner piece and support means within the triangular opening in the flanges to receive and fixedly support a relatively flat corner piece so that the corner piece is not required to have the configuration of the triangular opening in the frame.